Annexin A2的结构和功能及其与疾病的关系

Annexins是一类钙依赖性膜磷脂结合蛋白。Annexin A2是Annexins家族中的一个重要成员,存在于细胞膜、胞质和胞外。Annexin A2蛋白在细胞膜构架的形成、膜聚合、内吞和胞吐中均扮演重要角色。Annexin A2还参与某些病理过程,与心血管疾病、血液病、肿瘤等多种疾病相关。文章简要综述了Annexin A2分子的结构、生化特征、生物学功能及其与疾病的关系。     

Effect of hypothermia on renal sodium reabsorption

Summary The relationship between sodium reabsorption and oxygen consumption was studied in an isolated rabbit kidney preparation perfused with blood at 37, 28 and 19° C. When the temperature was lowered from 37° C to 28° C and to 19°C the rate of oxygen consumption and of the maximal P.A.H. excretion (Tm P.A.H.) decreased more than that of sodium reabsorption.TheQ ₁₀ for sodium reabsorption is about 1.8, while that for maximal P.A.H. excretion is 2.5. Some hypothesis on the possible mechanisms of the lowQ ₁₀ of the Na⁺ reabsorption are forwarded.Preliminary reports have been published [Boll. Soc. Ital. Biol. Sper.43, 1019–1023 (1966) and44, 1784–1787 (1967);45, 860–862 (1969) and45, 863–865 (1969)].     

Immunohistochemical localization of substance P and substance P receptor (NK1) in the olivary pretectal nucleus of the rat

The olivary pretectal nucleus (OPN) is the first central nucleus in the pupillary light reflex arc (PLR). Substance P (SP) is a neuropeptide present in the OPN. The present immunohistochemical study, performed at the ultrastructural level, aimed to determine the synaptic localization of SP and SP receptor in the OPN. Three types of SP-positive terminals were found. The most abundant type was of retinal origin, characterized by electron-lucent mitochondria and round vesicles, organized in glomerular structures, making asymmetric synaptic contacts with dendrites, and profiles containing pleomorphic vesicles, also making synaptic contacts with dendrites. The second type of SP-immunoreactive terminal contained electron-dense mitochondria and pleomorphic vesicles. This type made symmetric synaptic contacts and may originate from the ventral part of the lateral geniculate nucleus. The third type of SP-immunoreactive terminals contained electron-dense mitochondria, clear round vesicles, and made an asymmetric synaptic contact. This type originates from the contralateral OPN. SP receptors of the NK1 subtype were revealed to be on dendrites and were part of the glomerular-like arrangement. On account of the present observations, it can be concluded that retinal projections to the OPN use SP as a neuromodulator and synapse on NK1 receptor-containing dendrites of large neurons projecting to the Edinger-Westphal nucleus. Since SP also modulates the parasympathetic component of the PLR, we postulate that SP plays a modulating role in all components of the PLR.     

During active viscerocutaneous leishmaniasis the anti-P2 humoral response is specifically triggered by the parasite P proteins.

In this work we show that in the sera from dogs naturally infected with the protozoan parasite Leishmania infantum there are antibodies that react specifically against the parasite acidic ribosomal proteins LiP2a and LiP2b, and that each one of the Leishmania P proteins elicits a specific humoral immune response. Using synthetic peptides, the antigenic epitope of these proteins has been mapped in a single region located adjacent to the C-terminal domain highly conserved among the eukaryotic P proteins. The anti-P antibodies elicited during the Leishmania infection do not recognize the conserved C-terminal domain of the parasite P proteins, in contrast with the findings reported in Chagas' disease or systemic lupus erythematosus. The antigenic epitopes of the LiP2a and LiP2b are almost identical in amino acid sequence. No reactivity against Trypanosoma cruzi and human P proteins was found in sera from L. infantum-infected dogs.     

The morphogenesis of testicular degeneration induced in rats by orally administered 2,5-hexanedione

The neurotoxic hexacarbon 2,5-hexanedione (2,5-HD) produces testicular atrophy in experimental animals. To examine the morphogenesis of the testicular lesion, 1.0% 2,5-HD was provided in the drinking water of adult F-344 rats for up to 6 weeks. After 3 weeks of administration, there were occasional large vacuoles in the basal region of the germinal epithelium. At 4 weeks, these vacuoles were much larger and more numerous; electron microscopy demonstrated that they were derived from the smooth endoplasmic reticulum. The vacuoles were preferentially associated with stages 12, 13, 14, and 1 of the spermatogenic cycle. Additionally, at 4 weeks there was a significant decrease in the number of tubules in stages 7 and 13, and a concomitant increase in the percentage of tubules in stages 3, 5, and 6. By Week 5, most Golgi-phase and cap-phase spermatids were visibly affected, showing margination of nuclear chromatin, and were becoming dissociated from Sertoli cells. Frequent multinucleated giant cells were seen and electron microscopy of these cells suggested that they were derived from fused spermatocytes or spermatids. After 6 weeks, fewer giant cells were present, most tubules contained cellular debris, and many showed empty lumina encircled by a thin ring of cytoplasm near the basement membrane. Interstitial tissue appeared unaffected. These studies indicate that the Sertoli cell is probably an initial target for 2,5-HD action in the testis.     

A portable device for the rapid concentration of viruses from large volumes of natural freshwater

A portable device for the rapid concentration of viruses from natural freshwaters described and its performance in field use is evaluated. The system handled up to 500 litres of water in less than 90 min at a cost of only 2 pounds per sample. Where the samples contained sufficient bacteriophages for detection by direct plating the apparent phage recoveries were greater than 75%. Plant and animal viruses were also concentrated from waters with this system.     

Cell-mediated immunity in leprosy and transfer of delayed hypersensitivity reactions

Eighty-nine patients with leprosy, 65 classified as lepromatous and 24 as tuberculoid, were examined in this study. Skin test responses to protein antigens and dinitrochlorobenzene (DNCB) were depressed in lepromatous patients compared to controls. Tuberculoid patients did not exhibit a significant depression to microbial antigens, but they showed a definite depression in the ability to be sensitized with DNCB. The transfer of delayed hypersensitivity reactions to tuberculin, trichophytin, and lepromin (Fernandez and Mitsuda reactions) was accomplished in lepromatous and indeterminate leprosy patients using viable lymphocytes from donors presenting positive reactions to these antigens. The lepromin reaction was also transferred to patients with South American blastomycosis and cutaneous leishmaniasis. The positive reactions of adoptive immunity were confirmed by histologic examination of skin biopsies.     

Localization of substance P- and enkephalin-like immunoreactivity in relation to catecholamine-containing cell bodies in the cat dorsolateral pontine tegmentum: an immunofluorescence study

The distribution of tyrosine hydroxylase-, substance P- and enkephalin-immunoreactive neurons in the cat dorsolateral pons was studied using the indirect immunofluorescence method of Coons. To allow for the visualization of substance P- and enkephalin-immunoreactive cell bodies, colchicine was injected either in the ventricular space or in the cerebral tissue. The distribution of the tyrosine hydroxylase-immunoreactive cell bodies corresponded with the well-known distribution of catecholamine cells in this area of the brain. The observation of adjacent sections treated separately with tyrosine hydroxylase- and enkephalin-antiserum revealed that most catecholaminergic cells contain enkephalin-immunoreactivity. In addition to this catecholamine-enkephalin cell population, a moderate number of substance P-immunoreactive cell bodies was found in dorsolateral pons. The peribrachial nuclei were found to be densely supplied with substance P- and enkephalin-immunoreactive fibers, whereas the medial subdivisions, which contain the majority of the catecholamine cells in the dorsolateral pons, display a moderate number of immunoreactive fibers. These results are suggestive of interactions between peptide-containing and catecholaminergic neurons and also between-peptide-containing and non-catecholamine-containing neurons in the cat dorsolateral pons.     

Immunochemical characterization of mouse brain-associated theta (Thy-1) antigen.

The Thy-1 antigens or rat brain and thymus have been isolated and chemically characterized, but those of mice have not been identified. Moreover, it is uncertain whether the antigens are glycolipids or glycoproteins. This study with highly purified preparations of gangliosides GM₁, ¹GD_1a, GD_1b and GT_1b from bovine brain and several ganglioside fractions from mouse brain showed that Thy-1 activity does not reside in gangliosides, but rather in the chloroform-methanol-insoluble residue of brain remaining after extraction of gangliosides. The antigen could be solubilized from this residue with a non-ionic detergent. The antigenic activity of the solubilized preparation was heat-labile but resistant to periodate. The chemical properties of the Thy-1 antigen of mouse brain are discussed.     

Mutations in Steroid 21-Hydroxylase (CYP21)

The inherited inability to synthesize cortisol is termed congenital adrenal hyperplasia. More than 90% of cases are caused by 21-hydroxylase deficiency. This syndrome is characterized by signs of androgen excess and often mineralocorticoid deficiency. Steroid 21-hydroxylase (P450c2l) is a microsomal enzyme expressed in the adrenal gland that catalyzes conversion of 17-hydroxyprogesterone and progesterone to 11-deoxycortisol and deoxycorticosterone respectively. In man, this enzyme is encoded by the CYP21 (CYP21B) gene which is located in the HLA major histocompatibility complex along with a pseudogene, CYP21P (CYP21A). Mutations in CYP21 causing congenital adrenal hyperplasia are almost all generated by recombinations between CYP21 and CYP21P. These recombinations either delete CYP21 or transfer deleterious mutations from CYP21P to CYP21, a process termed apparent gene conversion. The degree of enzymatic compromise caused by each mutation is correlated with the clinical severity of the deficiency observed in patients carrying that mutation. © 1994 Wiley-Liss, Inc.